Michael Deacon is the Telegraph's Parliamentary Sketchwriter. He also writes regularly about TV.

Peep Show: time to go?

Peep Show has returned for its fifth series on Channel 4Â and is still the funniest British sitcom on TV at the moment.

Feckless at 40?Â David Mitchell and Robert Webb

I love it. But I'm wondering how much more of it I can take.

Not that the firstÂ episode was bad. It was, as ever, excellent.

But the lives of feckless flatmates Mark (David Mitchell) and Jeremy (Robert Webb) are becoming so pitiful that, sooner or later, they're almost bound to feel like killing themselves.

The episode was so dark, I had half a mind to do it myself.

When Peep Show started, five years ago, you felt you could take Mark and Jeremy's neuroses and failures relatively lightly.

Mark was in endless forlorn pursuit of Sophie (Olivia Colman), Jeremy's god-awful band was going nowhereÂ… But never mind they were in their twenties. They'd get over it, grow up, settle down and live normal lives. Eventually.

But now that they're older, Mark's ineptitude with women, and Jeremy's ineptitude full stop, are outright depressing.

Take the ending of the first episode. Mark's date, who he'd timidly decided was "the one", muttered that he was a "weird guy" who she didn't want to see again, and stalked out of the flat.

Jeremy taunted Mark; Mark told Jeremy to "f*** off". That wasn't wry or rueful or bittersweet. That was mutual loathing. I could feel myself developing a stomach ulcer just watching it.

Perhaps the writers should have a heart, make this the last series and let Mark and Jeremy go out on a high. Or at least a bearable low.

Because imagine them in another five years. Back, as they are at the start of every series, to square one: Mark still socially incompetent, Jeremy still jobless, both still single, both still stewing in their respective petty bitternesses. But aged 40.

What kind of soul-squashing catastrophes will they be inflicting on themselves, and each other, in middle-age?